There is an ongoing need for solid state circuits adapted to operate at higher and higher frequencies, including microwave frequencies. As used herein, the term “microwave” is intended to refer to frequencies at or above about 300 MHz, for example between 300 Mz and 3 GHz. Various transistor structures have been created that are capable of providing gain in such frequency ranges. A LDMOS (Lateral Diffused Metal Oxide Semiconductor) transistor is an example of such a transistor structure.
In some lateral transistor devices, such as a LDMOS transistor device, the source is typically coupled to the rear side of the substrate in which the transistor structure is formed. The source may be coupled by a highly doped region of the substrate, commonly known as a sinker structure, or a conductive through substrate via (TSV) to the rear side of the substrate.
Further improvements to the connection between the source and the rear surface of the substrate are desirable.